Contacting



All@ 29, 1950 w. A. HAGERBAUMER 2,520,717

coN'rAcrmG Filed Jan. 2, 1947 2 sheets-shea 1 AGENTR ,4 TTOPNE'Y Patented Aug. 29, 1950 CONTACTING William A. Hagerbaumer, Westfield, N. J., assignor to Socony-Vacuum Oil Company, Incorporated, a corporation of New York Application January 2, 1947, Serial No. 719,904

Claims.

This invention relates to a process and apparatus for contacting a solid with` a gas and is more particularly concerned with a contacting operation wherein the gas is a reaction mixture of at least two gaseous components. In a specific embodiment, the invention is concerned with combustion of gaseous fuel in air or other oxidizing gas in a bed of solid contact material in order to heat the latter; however, the invention isalso applicable to other chemical reactions and the solid contacting agent may be a catalyst for a gaseous reaction.

The specific embodiments discussed hereinafter are designed primarily for heating a moving bed of solid granular heat transfer agent and the invention will be described in connection with such operations, which are to be taken as exemplary only. Essentially, the invention lies in a means and method for providing a contact path through a bed of granular solid to which reactants are admitted in a manner to minimize the formation of zones wherein the reaction proceeds at an unduly high rate. To accomplish this end, in the case of two reaction components, one component is wholly introduced to one end of the reaction path in admixture with a relatively small proportion of the other component and the remainder of the other component is added as small increments along the contact path. This concept may be applied to catalyzed reactions such as the oxidation of sulfur dioxide or ammonia and also to the partial oxidation of organic compounds. The reaction may also be among three components with two wholly introduced at one end of the path and the other component added in successive increments. As an example of a three-component gaseous reaction, note may be taken of vapor phase alkylation of isoparaiiins. Thus, a mixture of isobutane and a vapor phase promoter such as propyl chloride may be introduced at one end of the path and a suitable olefin such as butylene may be added in successive increments to maintain the olefin concentration below that at which polymerization occurs.

Referring now to the exemplary operation of heating a granular heat transfer solid; this operation is advantageously conducted as a portion of a cyclic process for the manufacture of gaseous oleflns and the like. Thus, gas oil or crude petroleum is readily converted to high yields of ethylene by reaction at temperatures on the order of 1600 F. for contacting times of a fraction of a second, say 0.2 second. More refractory hy drocarbons su'ch as propane and ethane require higher temperatures and at still more elevated temperatures, acetylene can be produced.

In order to obtain the high temperature, short reaction time conditions required for these processes, the charge material is advantageously passed through a moving bed of highly heated granular solid and the gaseous reaction mixture is promptly quenched to avoid secondary reactions such as condensation to aromatics.

The apparatus and process of the present invention provide means for rapidly 'and eiiiciently heating granular solid in a substantially compact moving bed to afford a continuous Supply of hot granular solid for the reactor. To accomplish this purpose, the granular solid heat transfer agent is passed downwardly through a heating zone as a substantially compact, continuously moving bed. A plurality of burners extend downward into the .bed and are provided at the lower ends with burner tips from which issues a mixture of fuel and air. One of the name components supplied at the burner tip is in an amount insufficient to completely consume the other com- 'ponent supplied at this point. The balance of the inadequate component is furnished in increments along the path of flame propagation and the heat of combustion is thus partially dissipated as it is generated and excessive iiame temperatures which might damage the granular solid by fusion are avoided. The component supplied in increments may be either the fuel or the air but it is generally found desirable to supply all the fuel at the burner tip and bring the air in as increments. In preferred embodiments, the incremental air is supplied at points along the burner tube and also at a plurality of points thereabout to insure eiiicient mixing and combustion and propagation of the flame throughout the entire mass of granular solid.

These and other objects and advantages of the invention are more clearly understood by reference to the annexed drawings; wherein Figure 1 is a vertical section through a heater embodying the principles of the invention;

Figure 2 is a detail view of a burner tube assembly;

Figure 3 is a fragmentary vertical section offa modifled'type of heater; and

Figure 4- is a diagrammatic showing of the arrangement of elements according to a preferred embodiment.

Referring now tc Figure 1, recycled granular solid, tp be heated and supplied to a contacting reactor, is conducted from the top of an elevator or the like by a chute III to the top of a stratification of granular solid in the chute I8,

the stream of solids is introduced to the heater II by a rotating spout I2 having a bull gear I3 driven by motor I4. The bull gear and rotating spout assembly are carried by bearings indicated generally at I5 and the neck of the heater II through which the spout entersis provided with labyrinth batlles to which clean air or steam may be introduced to provide a seal against undue passage of gases in either direction through the neck.

The top of the heater II constitutes a hopper in which is maintained a bulk supply of the granular solid above a hopper floor I6. Granular solid is conducted from the hopper into the heating zone by a feed pipe I1. In the embodimentv of Figure 1 only one feed pipe II is employed and the granular solid is diverted by an insert I9 therebelow to give a bed having an upper surface lying at about the angle of repose of the solids. The Vangle of repose is eiected by the upward passage of gases therethrough and approaches the horizontal as the gas velocity approaches that which will suspend the solids. A plurality of burner tubes I8 extend downwardly into the moving bed to equal depths below the top surface thereof and the variation in the angle of repose with gas velocity must be taken into account in determining the position of the lower ends of the burner tubes I8.

Each of the burner tubes I8 comprises three concentric pipes for conducting gaseous fuel, primary air and secondary air into the burning zone. These three gaseous phases are supplied from plenum chambers dened by the hopper floor I6 and plates 20, 2| and 22. The inner pipe 23 of each of the burner tubes I8 opens to the upper plenum chamber between hopper floor I6 and plate 20'. 'Ihe intermediate pipe 24 opens to the second plenum chamber between plates 28 and 2I while the outer pipe 25 is open to the lower plenum chamber between plates 2I and 22. Gaseous fuel is supplied by a line 2'8 to the upper plenum chamber while primary and secondary air are supplied by lines 2'I and 28, respectively, to the intermediate and lower plenum chambers. The inner tube 23 and the outer tube 24 are open at the bottom and gases flowing therefrom are mixed by a conical insert 29 thus introducing a mixture of primary air'and gaseous fuel to the moving bed. Secondary air is discharged through orices and tubes from the outer pipe 25 at points along its length as more particularly described below in 'connection with Figure 2. The highly heated solid is withdrawn from the bottom of heater II through a series o1' ow control plates 30, 3| and 32 and is discharged by outlet 33 for transfer to the reactor.

As shown in Figure 2, the supply of gases to the several pipes of burner tube I8 may be made by means of threaded connections adapted to communicate, with suitable headers and manifolds not shown. The conical insert may be advantageously formed of an upper metal cone 34 (for example, stainless steel) which has a plurality of curving grooves 35 in the surface thereof to induce mixing of the fuel and primary air. A refractory cone 36 is advantageously 'secured to the metal cone 34'by an alloy bolt 31. This the cone 34 is adjusted to insure that the mixture of primary air and gaseous fuel -issues from the burner tip at high velocity to avoid combustion at the tip itself. Preheated air is used but it is supplied at such temperature that the mixture issuing from the tip is below its ignition temperature and combustion does not occui` until the mixture is further heated by penetration of the moving bed thus heating it to ignition temperature. The products of partial burning of the gaseous fuel in the primary air pass upwardly through the moving bed and the secondary air required for complete combustion is admitted to the moving bed from the space between pipes 24 and 25. This admission of secondary air may be accomplished by means of orifices in the pipe 25 as indicated at 40., These orifices are protected from direct contact with the granular solid by cylindrical shields 4| welded at their upper ends to the pipe 25. It will be noted -that this gives to the secondary air from-orices 48a single velocity component directed downwardly as it enters the moving bed, thus avoiding disturbances of the flow of combustion gases due to horizontal velocity components of the secondary air.

Advantageously, a substantial proportion of the secondary air is introduced to the bed Aat points horizontally spaced from the burner tube I8. Air tubes 42 are secured to the pipe 25 for this purpose and communicate with the interior thereof. It will be noted that the lower ends of the tubes 42 are also directed downwardly to thus avoid a horizontal velocity component of secondary air admitted in this manner.

As will be seen from Figure 1, the products of combustion pass upwardly from the moving bed of granular solid, are disengaged from the solid at the upper surface of the bed and enter a free space about the burner tubes I8 and below the plate 22 from which they are withdrawn by out- Y let port 43 for transfer to a suitable stack or economizer. If desired, means may be introduced to equalize the flow from various portions of the bed asby insertion of a baille plate having a number of orifices to throttle the gas to a desired velocity across the top of the bed.

Figure 3 shows an arrangement of heater II wherein a number of granular solid feed legs I'I are employed, each depending from a plate 44 which denes the iioor of the hopper. The burner tubes I8 in this gure may be that shown speciically in FigureZ and the space below plate 44 can be advantageously used for manifolds and headers. A second plate 45 may be used to set off the manifolding space from the heating zone and thus avoid difllculties arising from circulation of combustion gases about the manifolds. Figure 3 shows a. large number of feed pipes I'I but such a number is not essential as assembly is held in place by a collar 38 adjustably secured to the lower end of pipe 23 as by set screws. The collar 38 and the metal cone 34 are securely fastened'together by supports 39.

The gap between the lower end of pipe 24 and will be seen from reference to Figures 1 and 4.

Figure 4 represents, 'diagrammaticallm a vertical section through a reactor having the burner tubes I8 arranged on a triangular pattern. The secondary air tubes 42 are arranged about the burner tubes I8 in groups of 3. Since each of the secondary air tubes 42 extends half-way to.

the next adjacent burner tube I8, it will be seen that each burner tube I8 is surrounded by six points of secondary air introduction, one point at each angle of a regular hexagon having its center coincident with the center line of tube I8. As the products of partial combustion move upwardly through the moving bed of granular solid. they pass through a pluralityof levels of secondary air introduction. At each of these levels the moving gases surrounding each burner tube Il meet with additional air supplied at the wall of tube Il and at six points equally spaced thereabout. This resultsin highly eillcient mixing ofthe secondary air with the products of partial combustion thus giving a highly efficient combustion of the fuel and a high uniformity of flame temperatures along the path of flame propagation.

'I'his system is well adapted to automatic control. For example, referring to Figure l, va thermocouple 4i inthe moving bed can be employed-to actuate a valve 41 on the fuel supply line 20 thus adjusting the rate of fuel supply in accordance with temperature of the heated solid. A constant ratio between gaseous fuel and primary air is obtained by automatic control of valve 4l on line 21. This control is actuated responsive to orifice ilow meters 49 and 50 on the lines 2i and 21 respectively. The flow of second ary air may be advantageously maintained cona. hopper in the upper portion of said vessel be-4 low said inlet means, three plates spaced successively below said hopper floor extending across said vessel and defining an upper, a'lower and an intermediate plenum chamber, a plurality of fuel pipes extending through said Vthree plates downwardly into said vessel therebelow and communicatingvwith said upper chamber, said fuel Y pipes being arranged in a triangular `pattern with each three adjacent fuel pipes at the angles of identical equilateral triangles, a primary air pipe communicating with said intermediate chamber extending downwardly into said vessel below said plates about and coaxial with each of said fuel pipes, means at the lower end of each of said primary air pipes for mixing eiliuent therefrom with eiliuent from the fuel pipe coaxial therewith, a secondary air pipe communicating with said lower chamber extending downwardly into said vessel below said plates about and coaxial with each of said primary air pipes, each of said secondary air pipes having orifices therethrough, a plurality of feed tubes extending outwardly from each of said secondary air pipes along sides of said triangles to points about midway between adjacent pipes, the said tubes of adjacenty pipes being on dierent sides of said triangles, and the discharge of each of said tubes being downwardly directed, at least one tubular feedleg for conducting granular solid downwardly from said hopperto a level spaced downwardly from the lowermost of said plates and means to withdraw gas from the space between said level and the lowermost of said plates.

2. A contactor comprising a vertical vessel, inlet means to admit a granular solid to the upperportion of said vessel, outlet means to withdraw granular solids from the bottom of said vessel, three plates spaced successively below said inlet means extending across said vessel and defining an upper, a lower and an intermediate plenum chamber, a plurality of fuel pipes extending through said three plates downwardly into said vessel therebelow and communieating with said upper chamber, said fuel vpipes being arranged in a triangular pattern with each 6 three adjacent fuel pipes at the angles of identical equilateral triangles. a primaryv airpipe communicating with said intermediate chamber extending downwardly into said vessel below said plates about and coaxial with each of said fuel pipes, means at the lower end of each of said primary air pipes for mixing ei'liuent therefrom with eiiiuent from the fuel pipe coaxial therewith, a secondary air pipe communicating with said lower chamber extending downwardly into said vessel below said plates about and coaxial with each of said primary air pipes. each of said secondary air pipes having orifices therethrough, a plurality of feed tubes extending outwardly from each of said secondary air pipes along sides of said triangles to points about midway between.

adjacent pipes, the said tubes of adjacent pipes vbeing on diiferent sides of said triangles, and the discharge of each of said tubes being downwardly directed, at least one tubular feed leg for conducting granular solid downwardly from said inlet means to a level spaced downwardly from the lowermost of said-plates and means to withdraw gas from the space between said level and the lowermost of said plates.

3. A contactor comprising a vertical vessel, inlet means to admit a granular solid to the upper portion of said vessel, outlet means to withdraw granular solids from the bottom of said vessel, a plurality of fuel pipes extending downwardly into said vessel from the upper portion thereof, said fuel pipes being arranged in atriangular pattern with each three adjacent fuel pipes at the angles of identical equilateral triangles, a primary air pipe extending downwardly into said vessel about and coaxial with each of said fuel pipes, means at therethrough, a plurality of feed tubes extending outwardly from each of said secondary air pipes along sides of said triangles to points about midway between adjacent pipes, the said tubes of adjacent pipes being on different sides of said triangles, and the discharge of each of said tubes being downwardly directed, at least one tubular feed leg for conducting granular solid downwardly from saidv inlet means to a level spaced downwardly from said inlet means, means to separately supply duid material to said fuel pipes, said primary air pipes and said secondary air pipes, and means to withdraw gas from the space above said level.

4. A contactor comprising a, vertical vessel, inlet lmeans to admit a granular solid to theupper portion of said vessel, outlet means to withdraw granular solids from the bottom of said vessel, a plate in said vessel, constituting the floor of a hopper in the upper portion of said vessel below said inlet means, three .plates spaced successively below v said hopper iloor extending across said vessel, and defining an upper, a lower and an intermediate plenum chamber, a plurality of fuel pipes extending through said three plates downwardly into said vessel therebelofw and communieating with' said upper chamber, a primary air pipe communicating with said intermediate chamber extending downwardly into said vessel below said plates about and coaxial with each of said fuel pipes, means at the lower end of each of said primary air pipes for mixing eiiluent therefrom with efiiuent from the fuel pipe coaxial therewith, a secondary air pipe communicating with said lower chamber extending downwardly into said vessel below said plates about and coaxial with each of said primary airpipes, each of said secondary air pipes having orifices therethrough, a plurality of feed tubes extending outwardly from each of said secondary air pipes to points about midway between adjacent pipes. and the discharge of each of said tubes being downwardly directed, at least one tubular'feed leg for conducting granular solid downwardly from said hopper to a level spaced downwardly from the lowermost of said plates and means to withdraw gas from the space between said level and the lowermost of said plates.

5. A contacter comprising a Vertical vessel, inlet means to admit a granular solid to the upper portion of said vessel, outlet means to withdralw granular solids from the bottom of said vessel, three plates spaced successively below said inlet means extending across said vessel and dening an upper, a lower and anr intermediate plenum chamber, a plurality of /fuel pipes extending i through said three Iplates downwardly into said vessel therebelow and communicating with "said urpper chamber, a primary air pipe communicating with said intermediate chamber extending downwardly into said vessel below said plates about and coaxial with each of said fuel pipes, means at the lower end of each of said primary air pipes for mixing eiiiuent therefrom with eiiluent from the fuel pipe coaxial therewith, a secondary air pipe communicating lwith said lower chamber extending downwardly into said vessel below said plates about and coaxial with each of said primary air pipes, each of said secondary air pipes having orifices therethrough, a plurality of feed tubes extending outwardly from each of said secondary air pipes to points about midway between adjacent pipes, and the discharge of each of said tubes being downwardly directed, at least one tubular feed leg for conducting granular solid downwardly from said inlet means to a level spaced downwardly from the lowermost of said plates and means to withdraw gas from the space between said level and the lowermost of said plates.

6. A contacter comprising a vertical vessel, inlet means to admit a granular solid to the upper portionof said vessel, outlet means to withdraw granular solids from the bottom of said vessel, a, plurality of fuel pipes extending downwardly into said vessel from the upper portion therof, a primary air pipe extending downwardly into said vessel about and coaxial with each of said fuel pipes, means at the lower end of each `of said primary air pipesv for mixing ellluent therefrom with eflluent from the fuel pipe coaxial therewith, a secondary air pipe extending downwardly into said vessel about and coaxial with each of said primary air pipes, each of said secondary air pipes having orifices therethrough, a plurality of feed tubes extending outwardly from each of said secondary air pipes Ato points about midrway between adjacent pipes, and the discharge of each of said tubes lbeing downwardly directed, at least one tubular feed leg for conducting granular solid downwardly from said inlet means to a level spaced downwardly from said inlet means, means to separately supply fluid material to said fuel pipes, said primary air p ipes and said secondary air pipes, and means to withdraw gas from the space above said level.

7. A contacter comprising a vertical vessel, in-

let means to` admitv a granular solid to the upper portion of said vessel, outletmea'ns to withdraw granular solids from the bottom of said vessel, a plate in said vessel, constituting the oor of a hopper in .the upper portion of said vessel below said inlet means, three plates spaced successively below said hopper floor extending across said vessel and defining an upper, a lower and an intermediate plenum chamber, a plurality of fuel pipes extending through said three plates downwardly into said vessel therebelow and communicating with said upper chamber, a primary air pipe communicating with said intermediate chamber extending downwardly into said vessel below said plates about and coaxial with each of said fuel pipes, means at the lower end of each of said primary air pipesfor mixing effluent therefrom with eiiluent from the fuel coaxial therewith, a secondary air pipe communicating with said lower chamber extending downwardly into said vessel below said plates about and coaxial with each! of said primary air pipes, each of said secondary `air pipes having orifices therethrough, a plurality of feed tubes extending outwardly from each of said secondary air pipes to points about midway between adjacent pipes, at least one tubular feed leg for conducting granular solid downwardly from said hopper to a level spaced downwardly from the lowermost of said plates and means to withdrawn gas from the space between said level and the lowermost of said plates.

8. A contactor comprising a vertical vessel, inlet means to admit a granular solid to the upper portion of said vessel, outlet means to withdraw granular solids from the bottom of said vessel, three plates spaced successively below said inlet means extending across said vessel and dening an upper, a lower and an intermediate plenum chamber, a plurality of fuel `pipes extending through said three plates downwardly into said vessel therebelow and communicating with said upper chamber, a primary air pipe communicating with said intermediate chamber extending downwardly into said vessel below said plates about and coaxial with each of said fuel pipes, means at the lower end of each of said primary air pipes for mixing eilluent therefrom with effluent from the fuel pipe coaxialtherewith, a secondary air pipe communicating with said lowerchamber extending downwardly into said vessel below said plates about and coaxial with each of said primary air pipes, each of said secondary air pipes having orifices therethrough,

a plurality of feedtubes extending outwardly from each of said secondary air pipes to pointsl about midway between adjacent pipes, at least one tubular feed leg for conducting granular solid downwardly from said inlet means to a level spaced downwardly from the lowermost of said plates and means to withdraw gas from the space between said level and the lowermost of said plates.

9. A contactor comprising a Vertical vessel, inlet means to admit a granular solid to the upper portion of said vessel, outlet means to Lwithdraw granular solids from the bottom of said vessel, a plurality of fuel pipes ertending downwardly into said vessel from the upper portion thereof, a primary air pipe extending downwardly into said vessel about and coaxial with each of said fuel pipes, means at the lower end of each of sa-d fuel pipes, means at the lower end of each of said primary air pipesk for mixing eliluent therefrom with emuent from the. fuel pipe coaxial therewith. a secondary air pipe extending downwardly into said vessel about and coaxial with each of said primary air pipes, each of said secondary air pipes having orifices therethrough, a plurality of feed tubes extending outwardly from each of said secondary air pipes to points about midway between adjacent pipes, at least one tubular feed leg for conducting granular solid downwardly from said inlet means to a level spaced downwardly from said inlet means, means to separately supply fluid material to said fuel pipes, said primary air pipes and said secondary air pipes, and means to withdraw gas from the space above said level.

10. A burner comprising an inner tube, an intermediate tube thereabout, an outer tube about said intermediate tube, said inner and said intermediate tubes terminating in open adjacent ends to provide a burner tip, a conical throttling insert in said tip, said outer tube terminating in a closed end spacedfrom said tip, orifices in the wall of said'outer tube at spaced intervals along the said outer tube, cylindrical shields about said outer tube adjacent said oriilces, means connecting said outer tube and said shields on the sides thereof remote from said tip thus providing openings directed toward said tip, secondary tubes extending outwardly from said outer tube and communicating with the interior thereof, the outer ends of said secondary tubes being directed parallel to the axis of said outer tube 'and in the direction of said tip and means to separately supply fluid in each of said inner tube, said intermediate tube and said outer tube.

l1. A'burner comprising an inner tube, an intermediate tube thereabout, an outer tube about said intermediate tube, said inner and said intermediate tubes terminating in open adjacent ends to provide a burner tip, means to mix emuent from said inner and intermediate tubes at said tip, said outer tube terminating in a closed end spaced from said tip, orifices in the wall of -said outer tube at spaced intervals along the said outer tube, cylindrical shields about vsaid outer tube adjacent said oriilces, means connecting said outer tube and said shields on the sides thereof remote from said tip thus providing openings directed toward said tip. secondary tubes extending outwardly from said outer tube and communicating with the interior thereof, the outer ends of said secondary tubes being directed parallel to the axis of said outer tube and in the direction of lsaid tip and means to separately supply fluid to each of said inner tube, said inter.

mediate tube and said outer tube.

12. A burner comprising an inner tube, an intermediate tube thereabout, an outer tube about said intermediate tube, said inner and said intermediate tubes terminating in open adjacent ends to provide a burner tip, a conical throttllng insert in said tip, said outer tube terminating in a closed end spaced from said tip, orinces in the wall of said outer tube at spaced intervals along the said outer tube, secondary tubes extending outwardly from said outer tube and commimicating with the interior thereof. and means to separately supply fluid to each of said inner tube, said intermediate tube and said outer tube.

13. A burner comprising an inner tube, an in- 1 said intermediate tube, said inner and said intermediate tubes terminating in open adjacent ends to provide a burner tip, means tov mix efiiuent from said inner and intermediate tubes at said tip, said outer tube terminating in a closed endl spaced from said tip, orifices in the wall of said outer tube at spaced intervals along the said outer tube, secondary tubes extending outwardly from said outer tube and communicating with the interior thereof, and means to separately supply fluid to each of said inner tube, said intermediate tube and-said outer tube.

14. A process for heating granular solid material which comprises passing Isaid material downwardly as a substantially compact moving bed through a heating zone, injecting a mixture of gaseous fuel and insuilicient air for combustion thereof into said bed at a plurality of primary points in the lower portion thereof, injecting into said bed the additional air required for complete combustion of said fuel as separate increments on at least one level lspaced above said primary points, a nrst portion of the increment at each of said levels being introduced as streams directed downwardly from points substantially directly above said primary points and the remaining portion being introduced as streams directed downwardly from points equally spaced in said bed from the points of introduction of said first portion. l

l5. A process for heating granular solid material which comprises passing said material downwardly as a substantially compact moving bed through la heating zone, injecting a mixture of gaseous Vfuel and insumcient air for combustion thereof into said bed at a plurality of primary points in the lower portion thereof, injecting into said bed the additional air required for complete combustion of said fuel as separate increments on at least one level spaced above said primary points, a first portion of the increment at each of said levels being introduced as streams from points substantially directly above said primary points and the remaining portion being introduced as streams from points equally spaced in said bed from the points of introduction of said nrst portion. WILLIAM A. HAGERBAUMER.

REFERENCES CITED The foilowing references are of record in the ille of this patent:

UNITED STATES PATENTS termediatetubethereabout.anoutertubeabout 'l0 

2. A CONTACTOR COMPRISING A VERTICAL VESSEL, INLET MEANS TO ADMIT A GRANULAR SOLID TO THE UPPER PORTION OF SAID VESSEL, OUTLET MEANS TO WITHDRAW GRANULAR SOLIDS FROM THE BOTTOM OF SAID VESSEL, THREE PLATES SPACED SUCCESSIVELY BELOW SAID INLET MEANS EXTENDING ACROSS SAID VESSEL AND DEFINING AN UPPER, A LOWER AND AN INTERMEDIATE PLENUM CHAMBER, A PLURALITY OF FUEL PIPES EXTENDING THROUGH SAID THREE PLATES DOWNWARDLY INTO SAID VESSEL THEREBELOW AND COMMUNICATING WITH SAID UPPER CHAMBER, SAID FUEL PIPES BEING ARRANGED IN A TRIANGULAR PATTERN WITH EACH THREE ADJACENT FUEL PIPES AT THE ANGLES OF IDENTICAL EQUILATERAL TRIANGLES, A PRIMARY AIR PIPE COMMUNICATING WITH SAID INTERMEDIATE CHAMBER EXTENDING DOWNWARDLY INTO SAID VESSEL BELOW SAID PLATES ABOUT AND COAXIAL WITH EACH OF SAID FUEL PIPES, MEANS AT THE LOWER END OF EACH OF SAID PRIMARY AIR PIPES FOR MIXING EFFUENT THEREFROM WITH EFFLUENT FROM THE FUEL PIPE COAXIAL THEREWITH, A SECONDARY AIR PIPE COMMUNICATING WITH SAID LOWER CHAMBER EXTENDING DOWNWARDLY INTO SAID VESSEL BELOW SAID PLATES ABOUT AND COAXIAL WITH EACH OF SAID PRIMARY AIR PIPES, EACH OF SAID SECONDARY AIR PIPES HAVING ORIFICES THERETHROUGH, A PLURALITY OF FEED TUBES EXTENDING OUTWARDLY FROM EACH OF SAID SECONDARY AIR PIPES ALONG SIDES OF SAID TRIANGLES TO POINTS ABOUT MIDWAY BETWEEN ADJACENT PIPES, THE SAID TUBES OF ADJACENT PIPES BEING ON DIFFERENT SIDES OF SAID TRIANGLES, AND THE DISCHARGE OF EACH OF SAID TUBES BEING DOWNWARDLY DIRECT, AT LEAST ONE TUBULAR FEED LEG FOR CONDUCTING GRTANULAR SOLID DOWNWARDLY FROM SAID INLET MEANS TO A LEVEL SPACED DOWNWARDLY FROM THE LOWERMOST OF SAID PLATES AND MEANS TO WITHDRAW GAS FROM THE SPACE BETWEEN SAID LEVEL AND THE LOWERMOST OF SAID PLATES. 